JEOL 8200 Troubleshooting

[Dan R]

We had a severe humidity problem a few weeks back in the lab and water was condensing on the DP cooling tubes and dripping all over the internal parts of the machine. This has caused our DP heaters to short out in the past. I have since replaced the DP heaters but when i start the system, my 1st DP BACK pressure will not get below 1.5 Pa -- i switched the Rotary Pump and got the same result. Does this backing pressure seem reasonable? The DP heater never turns on and the system just stays stuck in the initial roughing mode ( i believe it should switch on DPs after ~20-30 min). Does this sound like a vacuum problem or does it look more like a circuit board was shorted and the logic isnt working properly. Any insights would be appreciated. Thanks!
-Dan

[Probeman]

This reminds me of the time we were having our new SX100 installed at Oregon and the Cameca engineer accidentally set the water chiller output temperature to around 60F (unfortunately it was also summer and relatively high humidity), and the cooling lines started sweating, just as you described.

Even more unfortunately, our high voltage power supply was underneath some of these cooling lines and the dripping water managed to short out the HV system completely.  We had to wait a couple of weeks to get a new HV supply from France!

[sem-geologist]

This reminds me of the time we were having our new SX100 installed at Oregon and the Cameca engineer accidentally set the water chiller output temperature to around 60F (unfortunately it was also summer and relatively high humidity), and the cooling lines started sweating, just as you described.

Even more unfortunately, our high voltage power supply was underneath some of these cooling lines and the dripping water managed to short out the HV system completely.  We had to wait a couple of weeks to get a new HV supply from France!

Probeman, knowing that you have dedicated engineer I am just wondering:
Was it HV tank or HV control board, or HV input PSU? HV tank would be very hard to damage as it is completely sealed, PSU is just converting the 220 AC into 28V DC with toroidal transformer, which should be soaked in water to short anything (and there is no water pipes above). HV control board has its main power transistors cooled by water at the bottom of the board (and it is at the bottom just in case of condensation). In case of any condensation only those transistors would be affected and it is very easy to replace and suitable replacement parts are plenty. That would had cost less time and money than to ship a new card from France to States. Sorry for the question, but just wonder how bad the condensing had to be at 15.5 C ? What normal temperature Your chillers are set? Our chillers are set to 20 C (68 F), where room temperature is about 22-23 C (71-74 F).

P.S.: I remember some funky days when I started to work on our probes, our SX 100 was temporary connected to the tap water, while chiller was on repair, and that was during cold winter and tap water temperature was 6 C (43 F), and there were no issues (maybe dry winter air at room (RH < 20%) prevented condensation). But the repair took substantially longer till summer (when tap water had about 15 C (59 F), but room humidity increased to 50% too).  It is not that I would advice such a thing - currently I would rather shutdown machine completely than run it on the tap water, but for reason of T instabilities and high iron content in tap water than condensation.

[Probeman]

This reminds me of the time we were having our new SX100 installed at Oregon and the Cameca engineer accidentally set the water chiller output temperature to around 60F (unfortunately it was also summer and relatively high humidity), and the cooling lines started sweating, just as you described.

Even more unfortunately, our high voltage power supply was underneath some of these cooling lines and the dripping water managed to short out the HV system completely.  We had to wait a couple of weeks to get a new HV supply from France!

Probeman, knowing that you have dedicated engineer I am just wondering:
Was it HV tank or HV control board, or HV input PSU? HV tank would be very hard to damage as it is completely sealed, PSU is just converting the 220 AC into 28V DC with toroidal transformer, which should be soaked in water to short anything (and there is no water pipes above). HV control board has its main power transistors cooled by water at the bottom of the board (and it is at the bottom just in case of condensation). In case of any condensation only those transistors would be affected and it is very easy to replace and suitable replacement parts are plenty. That would had cost less time and money than to ship a new card from France to States. Sorry for the question, but just wonder how bad the condensing had to be at 15.5 C ? What normal temperature Your chillers are set? Our chillers are set to 20 C (68 F), where room temperature is about 22-23 C (71-74 F).

P.S.: I remember some funky days when I started to work on our probes, our SX 100 was temporary connected to the tap water, while chiller was on repair, and that was during cold winter and tap water temperature was 6 C (43 F), and there were no issues (maybe dry winter air at room (RH < 20%) prevented condensation). But the repair took substantially longer till summer (when tap water had about 15 C (59 F), but room humidity increased to 50% too).  It is not that I would advice such a thing - currently I would rather shutdown machine completely than run it on the tap water, but for reason of T instabilities and high iron content in tap water than condensation.

At that time (2006) we had not hired our in-house instrument engineer so the Cameca engineer was working alone (I think it was only his 2nd EPMA install). Anyway, he was so embarrassed he didn't want to talk about it, and I didn't want to make him feel any worse so I didn't ask for details.

At the time we still had the SX50 still running in another room, so I just told him don't worry about it and went back to work on the old instrument!

When we moved to the new building a few years later we ended up moving both instruments, but by then it was all history and we had our own instrument engineer.